As the demand for faster, smaller electronic products with increased functionality is increased, some designers have turned to system-in-package (SIP) solutions. A SIP typically includes several different types of integrated circuits (ICs) integrated into a single IC package. However, in recent years, stacked packaging schemes, such as package-on-package (POP) configurations, have been used in place of SIP's. Typically, by allowing stacking of different semiconductor packages, the required footprint size for a semiconductor package in an electronic product can be reduced. Furthermore, because some stacked packages, such as POP packages, provide a modular solution by allowing different combinations semiconductor packages to be stacked, designers can generally design different types of electronic devices using a few single semiconductor package footprints.
Some types of integrated circuits (ICs), including those used in stacked packages, are known to radiate a relatively large amount of electromagnetic energy during periods of operation. For example, microprocessors and other digital processing devices are recognized as major sources of electromagnetic radiation in computer systems. The electromagnetic energy radiated by such devices can interfere with the operation of other devices or circuits in the vicinity of the radiating IC, including those ICs in the same stacked package, and is therefore generally undesirable.
A number of techniques have been used in the past to reduce the level of electromagnetic interference (EMI) emanating from an IC, or to protect ICs from EMI. Typically such techniques require that a generally conductive cage structure be formed around the IC using a stamped sheet metal cage member that can have a plurality of legs spaced about a periphery thereof. The cage member is then placed over the IC package and is coupled to a corresponding ground pad on an underlying circuit board. The ground pads of the circuit board are each conductively coupled to a ground plane of the circuit board using, for example, via connections. In this manner, the generally conductive shield for blocking EMI, known as a Faraday cage, is formed around the IC. However, the use of conventional Faraday cages in stacked packaging schemes, such as POP packaging, typically increases the overall dimensions of the package and can eliminate at least a portion of the sizing advantages originally obtained through stacked packaging schemes.